The Graft Engineering Laboratory (GEL) is the bone marrow tissue bank for the clinical research project of this program. Personnel of this laboratory are responsible for all aspects of bone marrow, peripheral blood stem cell and core blood graft processing and quality assurance. This laboratory is a self-standing facility which is separate from the blood bank in both space and personnel. The laboratory provides basic tissue bank services as a core resource for the clinical projects and collaborates within its scope of activities with the research projects of this program. This laboratory will also pursue "developmental" projects necessary for definition and refinement of such tissue bank services as defining optimal storage, collection of media and anticoagulants for graft processing, engineering scale-up based on the respective research protocol, applications of positive stem cell selection technology and the Q.C. of graft products based on real time flow cytometry. This laboratory also serves as a core resource for other transplant centers: teaching personnel from these centers and disseminating information regarding tissue bank issues and ex vivo graft processing.